问题补充:
The letters for the boss on his desk but he didn’t read them until three days later.
A. was put
B. put
C. has put
D. were put
答案:
A. was put
B. put
C. has put
(答案→)D. were put
解析:考查被动语态。本句的主语是the letters,与动词put构成被动关系,故使用过去分词的形式。句意:给老板的信被放在桌子上,但是知道3天以后他才看见。故D正确。